I think it's more that a lot of young feminist women throw their feminist ideas out when they get married and want to have kids. It's one thing to say you don't need men, and went to work as much as men when you are in college. It's quite another once you actually are having kids and decide that maybe staying at home while your husband supports you isn't so bad after all.
Similarly, it's one thing for a college age women to believe women should be advantaged in education, in job hiring, in business ownership, etc. It's quite another when it's her husband who may lose a job or her son who may be disadvantaged in school.
I've certainly seen a lot of women re-evalaute their feminist goals as they get older, but obviously some stay feminists forever. Feminism overall has been dying in many western countries including the U.S., although that's not to say feminist organizations no longer have influence, they do.